mda-7 In combination with bevacizumab treatment produces a synergistic and complete inhibitory effect on lung tumor xenograft.

Bevacizumab, a humanized monoclonal antibody against vascular endothelial growth factor (VEGF), has shown antitumor activity by inhibiting tumor angiogenesis in preclinical and clinical studies. However, bevacizumab monotherapy does not induce complete tumor regression. Therefore, additional treatments must be combined with bevacizumab to promote tumor regression. We previously showed that melanoma differentiation associated gene-7 (mda-7) protein exerts potent antitumor and antiangiogenic activity. Thus, in this study, we investigated the therapeutic effects of mda-7 in combination with bevacizumab using lung cancer as a model. In vitro, treatment of human umbilical vein endothelial cells with conditioned medium from Ad-mda7 plus bevacizumab-treated lung tumor cells showed reduced VEGF ligand-receptor binding, and decreased cell survival, resulting in growth arrest and apoptosis. In vivo, treatment of subcutaneous lung tumor xenografts with bevacizumab plus Ad-mda7 resulted in significant tumor growth inhibition and improved survival compared to tumor growth in control mice. Furthermore, tumors in all the Ad-mda7 plus bevacizumab-treated mice completely regressed, and these were tumor free through the study's end. Molecular analysis showed enhanced tumor cell apoptosis and reduced VEGF and CD31 expression in Ad-mda7 plus bevacizumab-treated tumors. Thus, Ad-mda7 and bevacizumab treatment produces a synergistic and complete therapeutic effect against human lung cancer.

Antivascular therapy of oral tongue squamous cell carcinoma with PTK787.

OBJECTIVES/HYPOTHESIS: Vascular endothelial growth factor (VEGF) is an important mediator in tumor vascularization, growth, and metastasis. We investigated whether blockade of the VEGF receptor (VEGF-R) signaling pathway by the tyrosine kinase inhibitor PTK787 combined with CPT-11, a semisynthetic camptothecin analogue, can inhibit the tumor growth and angiogenesis of squamous cell carcinoma of the oral tongue in an orthotopic nude mouse model. METHODS: JMAR human oral squamous cell carcinoma cells were injected into the tongues of nude mice. Seven days later, the mice were randomized to receive a placebo, daily oral PTK787, weekly CPT-11 injection, or PTK787 plus CPT-11. After 4 weeks of treatment, the mice underwent necropsy, and the tongue tumors, cervical lymph nodes, and lungs were removed for immunohistochemical analyses. RESULTS: CPT-11, PTK787, and PTK787 plus CPT-11 significantly decreased tumor volumes and prolonged survival. The combination treatment group had the most significant decrease in volume and increase in survival. PTK787 alone or in combination with CPT-11 reduced the phosphorylation of VEGF-R in tumor cells and tumor-associated endothelial cells, was associated with decreased microvessel density, a decreased proliferative index, and an increased apoptotic index. PTK787 alone or the combination therapy resulted in apoptosis of both tumor cells and tumor-associated endothelial cells. CONCLUSIONS: These results suggest that targeting VEGF-R tyrosine kinase activity can be an effective therapeutic approach in squamous cell carcinoma of the oral tongue.

Expression of CXCR1 and CXCR2 receptors in malignant melanoma with different metastatic potential and their role in interleukin-8 (CXCL-8)-mediated modulation of metastatic phenotype.

In the present study, we examined the autocrine/paracrine role of IL-8 in melanoma growth and metastasis by analyzing the expression and functional significance of IL-8 receptors, CXCR1 and CXCR2 in human malignant melanoma cells with different metastatic potential. CXCR1 and CXCR2 mRNA and protein levels were analyzed by reverse trannscriptase-based polymerase chain reaction, immunohistochemistry, immunoprecipitation, flow cytometry and ligand binding assay in melanoma cells in vitro and xenografted in nude mice. Melanoma cells constitutively expressed CXCR1 and CXCR2 mRNA and protein. Highly metastatic A375SM cells expressed higher levels of CXCR1 and CXCR2 mRNA and protein in vitro and in vivo as compared to low metastatic A375P and non-metastatic SBC-2 melanoma cells. Treatment of SBC-2 and A375P cells with exogenously added recombinant IL-8 significantly enhanced their proliferation and invasive potential. Further neutralizing antibodies to CXCR1 and CXCR2 inhibited proliferation and invasive potential of unstimulated and IL-8-stimulated A375P cells. In summary, the data suggest that constitutive expression of CXCR1 and CXCR2 play an important role regulating the IL-8-mediated metastatic phenotype in human malignant melanoma cells.

Monocyte/macrophage recruitment, activation and differentiation modulate interleukin-8 production: a paracrine role of tumor-associated macrophages in tumor angiogenesis.

Tumor-associated macrophages (TAM) have been shown to play an important role in tumor angiogenesis. The purpose of this study was to determine whether monocyte recruitment, activation and differentiation mediated by monocyte chemotactic protein-1 (MCP-1) and macrophage colony stimulating factor (M-CSF) modulate the expression of the angiogenic factor, Interleukin (IL)-8. Isolated human peripheral blood monocytes secreted low basal levels of IL-8. Incubation of monocytes with M-CSF or MCP-1 resulted in an up-regulation of IL-8 mRNA and protein expression. The differential expression of IL-8 by monocytes following MCP-1 and M-CSF treatments involved activation of the NFkB transcription factor. Further activation with lipopolysaccharide (LPS) caused an increase in IL-8 secretion in monocytes but not in monocyte-derived macrophages (MDM). MDM-conditioned media significantly up-regulated IL-8 expression in human malignant melanoma cells in vitro. In summary, we demonstrated that MCP-1 and M-CSF, critical for monocyte recruitment, activation and differentiation, differentially regulate IL-8 expression and may play an important role in monocyte/macrophage-mediated tumor angiogenesis.